Atherectomy system with imaging guidewire

ABSTRACT

Systems and methods of increasing blood flow in a blood vessel with ultraluminal plaque. One disclosed method includes inserting an imaging guidewire into the blood vessel to the intraluminal plaque, propelling a catheter with a working head over the guidewire towards the distal end of the guidewire, scanning with the imaging guidewire to generate a cross-section image, radially positioning the catheter using a positioning element, monitoring the image to ascertain that the working head is properly positioned and operating the working head to remove the plaque. A computerized system designed, constructed and configured to perform the methods is further disclosed.

This application claims priority from U.S. Patent Application 60/419,087filed on Oct. 18, 2002.

FIELD AND BACKGROUND OF THE INVENTION

The present invention is directed to minimally invasive surgical systemsand methods of use thereof. More specifically, the present invention isdirected to computerized systems for operation of atherectomyinstruments and methods for intravascular surgery to increase blood flowin a lumen of a blood vessel. The disclosures of U.S. Pat. Nos.5,350,390, 5,806,404 and 5,697,459, issued to Sher, are incorporatedherein by reference in their entirety.

Atherosclerosis is the principal cause of heart attacks, stroke,gangrene and loss of function of extremities. It accounts forapproximately 50% of all mortalities in the USA, Europe and Japan.Atherosclerosis is characterized by a build-up of fatty deposits in theintimal layer of a patient's blood vessels. Very often over time, whatis initially deposited as relatively soft cholesterol-rich atheromatousmaterial hardens into a calcified atherosclerotic plaque. Such atheromasrestrict the flow of blood, which results in chest pain or even in casessevere restriction, to heart attack. Restriction of blood flow, whichleads to heart attack, is also explained by another mechanism known asvulnerable plaque. It happens to people that do not have severelynarrowed arteries. In fact the vulnerable plaque may be buried insidethe artery wall and may not always bulge out and block the blood flowthrough the artery. Inflammation combined with other stress e.g., highblood pressure can cause the covering over the plaque to crack andbleed, spilling the contents of the vulnerable plaque into the bloodstream. Blood cells that recruit to the site of injury can form a clotlarge enough to block the artery. It is of enormous importance that thephysician will have the capability of imaging the lesion morphologicallyas well as the plaque composition. There are imaging techniques thatperform these tasks. The modalities of imaging techniques will bedetailed later.

The present therapeutic strategies for severe atherosclerosis incoronary arteries rely on angioplasty procedures (e.g., percutaneoustrans-luminal coronary angioplasty (PTCA), atherectomy devices, stentimplantation, excimer laser angioplasty, etc.), and coronary arterybypass surgery (CABG). Transluminal angioplasty refers to a technique ofdilating significantly blocked arteries from inside, thus avoiding theneed for much more extensive surgical intervention (CABG).

Conceptually, atherectomy devices have the advantage of positivelyremoving the plaque. In the balloon (PTCA) and the stent procedures theplaque is not removed but rather pushed towards the blood vessel wall.Several kinds of atherectomy devices are currently available but theirperformances have not stood up to the expectations and will be discussedlater. A major disadvantage of the stent is that it causes in-stentrestenosis, a phenomenon that will be explained later. Stentimplantation involves deployment of a foreign body that evokes areaction of the immune system. The stent and the balloon have theadvantage that the procedure is relatively simple and easy to use.

Today the stent is the common procedure for clearing blocked arteries(97% of more than 2 million procedures world wide). Atherectomy devicesare used only for specific procedures such as debulking of calcifiedlesions where it is difficult to open the lesion with the balloon.

To date none of the available techniques provides a total safe andeffective solution to blocked arteries. The problems that still exist inclearing blocked arteries are described below:

Restenosis—

Restenosis is re-occlusion of a peripheral or coronary artery followingtrauma to the artery caused by efforts to clear an occluded portion ofthe artery by angioplasty, such as, balloon dilation, stentimplantation, atherectomy or laser ablation treatment. The rate ofrestenosis following treatment with these angioplasty procedures isabout 30-50% depending upon the vessel location, lesion length and anumber of other variables. Restenosis occurs also in grafts that areused to bypass blocked arteries. Restenosis results in significantmorbidity and mortality and frequently necessitates furtherinterventions, such as repeat angioplasty or coronary bypass surgery.Thus, there is a need for methods and devices for preventing and/ortreating restenosis. Preferably, these methods and devices should bespecific in their effect, easy to administer, and effective in the longrun with minimal adverse side effects. The processes responsible forrestenosis are not completely understood.

One aspect of restenosis may be simply mechanical, caused by the elasticrebound of the arterial wall. Another aspect of restenosis is believedto be a natural healing reaction to the injured arterial walls that weredamaged by angioplasty procedures. The final result of the complex stepsof the healing process which involve local inflammation is intimalhyperplasia, and migration and proliferation of medial smooth musclecells, until the artery is again occluded.

The existing, FDA approved, atherectomy devices have shown a high rateof restenosis (30-50%). Atherectomy devices have also additionaltechnical problems. The AtheroCath (Guidant) is complex to use, ispushed across the lesion and offers inconsistent results. It has a highrate of blood vessel perforation. The Rotablator (Boston Scientific) isapplicable only to moderate to heavily calcified atherosclerotic plaquelesions. It does not cut the plaque but rather pulverizes it whilerotating at a very high speed. This causes problem of heating the bloodvessel and also to the phenomenon known as No Reflow in which blood doesnot flow in the vessel even though the lesion was opened.

In another type of atherectomy device, the cutting head does not rotate.An example of this type of device is U.S. Pat. No. 5,409,454 toFischell. In this type of device, the cutting head is first pushedacross the lesion and then pulled back. While pulled back the cuttinghead shaves the atheroma. Pushing the catheter across the lesion causestrauma to the blood vessel.

My U.S. Pat. No. 5,350,390 describes an atherectomy device, thataddresses the trauma problem. However, my own earlier teachings do notinclude the idea that removal of a lesion may begin prior to transversalof the lesion by a guidewire. This serious inherent disadvantage isaddressed by the teachings of the present invention, as will be detailedhereinbelow. In order to differentiate the claimed invention from thoseearlier teachings, the invention will be referred to hereinbelow asApparatus for Removal of Intraluminal Occlusions (ARIO)

In-Stent Restenosis—

The mechanical aspects of restenosis have been successfully addressed bythe use of stents to prevent elastic rebound of the vessel, therebyreducing the level of restenosis for many patients. The stent, though,has created a new problem called in-stent restenosis, namely theoccurrence of excessive late intimal hyperplasia due to excessive cellproliferation that can restrict blood flow within the stent itself.In-stent restenosis occurs in 20-30% of stent procedures and in manycases CABG is required to solve the problem.

Brachytherapy and drug coated stents are approaches aimed to reducein-stent restenosis. Brachyterapy provides only partial solution toin-stent restenosis. The drug coated stents succeeded in reducingin-stent restenosis from 20-30% to 5-9% but failed to eliminate it. Thedrug-coated stent is a new procedure. In follow-up tests, problems suchas late incomplete apposition emerged, however no long-term results arecurrently available.

Existing atherectomy devices such as the Rotablator and AtheroCath weretested for clearing in-stent restenosis, but the results weredisappointing. ARIO, due to its mild mode of operation is a suitablecandidate for clearing in-stent restenosis.

Perforation—Coronary artery perforation is a rare but importantcomplication of percutaneous revascularization. Perforation has beenreported in lesions treated with PTCA and Stents and at much higher ratein atherectomy devices. During PTCA or stenting perforation may occur asa consequence of guidewire advancement, balloon inflation or balloonrupture. Regardless of the device, the risk of perforation is increasedwhen complex lesion is present (chronic total occlusion, vesselbifurcation, severe tortuosity in artery). Clinically, coronaryperforation is associated with a high incidence of death.

Total Occlusions (TO) is a formidable obstacle for physicians.Physicians cannot see the path for the guidewire through the TO becausethe flow of the angiography contrast media is stopped by the blockage.There is a higher risk of perforation or damaging the vessel than withnormal angioplasty. U.S. Pat. No. 6,228,076 to Winston is an example ofcontrolling the path of the guidewire across a lesion using OCT. Anotherexample for TO crossing is U.S. Pat. No. 6,120,516 to Selmon.

Bifurcation: Percutaneous coronary intervention (PCI) in bifurcationlesions is challenging. It has lower procedural success and high ratesof restenosis compared with non-bifurcation PCI.

A great part of the problems described above can be solved if thephysician is provided with means for imaging the arteries. An importantand standard imaging modality is angiography. However, angiographyenables the physician to see only a general view of the arteries, wherethe details of the plaque are not clear. Several modalities that cangive a detailed image of the plaque have been suggested. Thesemodalities allow the physician to visualize the morphology as well asthe composition of the plaque. Subsequently, the physician can positionthe working head of the intraluminal catheter at a desired location.This procedure could minimize remarkably the risk of blood vesselperforation.

The imaging modalities can be classified in the following hierarchicalmanner:

There are two types of blood vessel imaging techniques, non-invasive andminimally invasive. The non-invasive modalities include CT (X-rayComputer Tomography), MRI (Magnetic Resonance Imaging), ECBT (ElectronBeam Computer Tomography), etc. In current non-invasive technology theresolution of the image is poor and therefore this type of imaging canbe used for a general view of the arteries. The minimally invasiveimaging can be divided into two classes: The first incorporates animaging sensor into or on the catheter. This class is exemplified byU.S. Pat. No. 4,794,931 to Yock, which describes an atherectomy devicewith ultrasonic imaging capabilities.

The second class incorporates a sensor into a guidewire. The secondclass can be divided into two sub-classes. The first sub-class producesa cross sectional image of the lumen e.g., IVUS (IntravascularUltrasound)—U.S. Pat. No. 6,459,921 to Belef, OCT (Optical CoherenceTomography)—U.S. Pat. No. 6,445,939 to Swanson, MRI (Magnetic ResonanceImaging)—U.S. Pat. No. 6,377,048 to Golan. This sub-class is relevant tothe present invention, as the operation of the device is based on thefact that the physician can see a cross sectional view of the lumen.

The second sub-class does not provide a cross sectional image of thelumen. It provides other kind of information related to the lumen e.g.,Thermography supplies thermal mapping of the interior of the lumen, U.S.Pat. No. 6,228,076 to Winston, describes a system which receivesinterferometric data from the tissue, etc.

Prior art describes a device that incorporates an imaging guidewire thatcan produce a cross sectional view of the lumen into an intravascularcatheter. U.S. Pat. No. 5,938,609 to Pomeranz describes an imagingguidewire with an ultrasound sensor. The movable imaging guidewireincludes a fixed guidewire tip attached to its distal end. The movableimaging guidewire is first positioned within the vascular system so thatits fixed guidewire tip extends beyond the stenosed region, and than theintravascular catheter is inserted over the movable imaging guidewire.This mode of operation renders it suitable for balloons procedures. Thedisadvantages of this type of movable imaging guidewire are similar tothe standard guidewire, i.e., the mechanical requirements of pushabilityand crossability are high. The operational disadvantage is high risk ofperforating the blood vessel or in case the occlusion is too severe theguidewire cannot cross it.

SUMMARY OF THE INVENTION

The present invention is directed to improvements of ARIO. The uniquefeatures of ARIO allow clearing of blocked arteries, removing vulnerableplaque, clearing in-stent restenosis, opening totally occluded arteriesand removing plaque at bifurcation.

It is the object of the present invention to provide a minimallyinvasive device for removing intraluminal occlusions in a safe, gentleand controlled manner.

It is the object of the present invention to provide a minimallyinvasive device that is guided by a non-crossing the lesion imagingguidewire.

It is the object of the present invention to provide an imagingguidewire that is not required to cross the lesion by itself. It crossesthe lesion together with the catheter. This reduces the mechanicalrequirement of the guidewire. It also eases the physician's work andreduces blood vessel trauma or perforation.

It is another object of the present invention to provide an atherectomydevice that cuts atheroma in a gentle manner, thus reducing restenosis.

Another object of the present invention is to provide an atherectomydevice that cuts and remove in-stent restenosis in a gentle manner.

It is a further object of the present invention to provide anatherectomy device that cuts the atheroma safely, reducing the risk ofartery perforation.

A still further object of the present invention is to provide anatherectomy device that gives the physician a real time arterycross-section image.

A still further object of the present invention is to provide anatherectomy device which includes balloons for radially positioning ofthe working head.

A still further object of the present invention is to provide anatherectomy device that allows the physician to control the longitudinalposition and orientation of the working head.

A still further object of the present invention is to provide anatherectomy device that allows the physician to control the lumen'scross sectional area to be excised.

A still further object of the present invention is to provide anatherectomy device that enables opening of total occlusions.

A still further object of the present invention is to provide anatherectomy device that enables removal of atheroma at bifurcation.

A still further object of the present invention is to provide anatherectomy device which includes means for aspirating debris of theatheroma.

A still further object of the present invention is to provide anatherectomy device which includes lumen for supplying therapeutic liquidto the site of atheroma.

According to these and further objects of the present invention, whichwill become apparent as the description thereof is presented below; thepresent invention provides an atherectomy device which includes:

-   -   A catheter assembly having a distal portion and adapted for        insertion into a patient, said catheter assembly including an        actuator and controller/computer unit;    -   A piston located within the distal portion of the catheter        assembly and adapted for simultaneous longitudinal and        rotational movement therein, the first piston including an        endless wave-shaped groove defined in a circumferential surface        thereof;    -   At least one ball retained for revolving motion in a recess        defined in an interior surface of the distal portion of the        catheter assembly, said ball projecting into and received by        said groove to force said piston to rotate about its        longitudinal axis in response to longitudinal movement of said        piston;    -   A working head secured to said piston for simultaneous        longitudinal and rotational movement together with said piston;    -   Positioning balloon located on the circumference of the catheter        distal end;    -   An imaging guidewire designed and constructed to position an        operative portion of a catheter before a plaque (i.e. the        guidewire does not traverse the plaque).

The imaging guidewire of this invention is unique in its mode ofoperation and its construction. In prior art the imaging guidewire thatcan produce a cross sectional image is required to cross the lesion.This requirement is problematic. Treating more calcified and/or longerlesions, pose higher risk of causing trauma to the blood vessel orperforation. ARIO's mode of operation does not require that the imagingguidewire will cross the lesion by itself. First, the physician insertsthe imaging guidewire up to the lesion and then slides the catheter overthe imaging guidewire up to the distal end of the imaging guidewire.Crossing the lesion is done by the catheter together with the imagingguidewire. The catheter advances slowly. The physician can see where heis heading and can control the radial position of the catheter with thepositioning balloons, prior to operating the working head. Thisprocedure eases the physician's work and minimizes blood vesselperforation.

In regard to the imaging guidewire technical requirements:

ARIO's imaging guidewire must withstand the following requirements:

-   -   1) Steerability—to allow the physician to direct the guidewire        into the desired branch. A common solution is by manufacturing        the guidewire with a bend at its distal end.    -   2) Flexibility—to allow easy advancement of the guidewire in        curved blood vessel.    -   3) Torqueability—is needed because the distal tip of the        guidewire is rotated from its proximal end.        However the fact that ARIO's mode of operation does not require        that the imaging guidewire will cross the lesion by itself,        markedly eases the pushability (axial force) and crossability        (shape of the distal tip) requirements.

An additional technical advantage of the non-crossing the lesion imagingguidewire lies in the fact that the distal tip can be relatively large.This eases the incorporating of an imaging sensor in the distal tip. Forexample the distal tip of this invention can be 800 microns in diameter,while the rest of the guidewire is 350 microns in diameter. The largerthe diameter of the sensor, the better is the image quality. Prior artteaches an imaging guidewire that has a small diameter along itsentirety. U.S. Pat. No. 6,445,939 to Swanson describes an OpticalCoherence Tomography (OCT) imaging guidewire, that is 350 microns(0.014″) in diameter along its entirety which results in reduced imagequality.

The present invention further provides a method of removing intraluminalocclusions which includes the following steps:

-   -   (a) Inserting an imaging guidewire into the blood vessel up to        the occlusion, without crossing the lesion;    -   (b) Sliding the catheter over the imaging guidewire up to the        distal end of the imaging guidewire;    -   (c) Securing proximal end of imaging guidewire to imaging        guidewire motor;    -   (d) Connecting therapeutic infusion pump;    -   (e) Connecting debris vacuum pump;    -   (f) Operating balloon pumps and equally pressurizing the        positioning balloons;    -   (g) Scanning the blood vessel with the imaging system to produce        a cross section image of the blood vessel;    -   (h) Radially positioning the working head in a desired location        by non-equally pressurizing the positioning balloons    -   (i) Operating the working head;    -   (j) Repeating steps (g) to (i) until the desired result is        achieved;    -   (k) Deflating positioning balloons;    -   (l) Advancing the catheter distally; and    -   (m) Repeating steps (f) to (l) until the lesion is crossed.

Thus, according to one aspect of the present invention there is provideda method for reducing restriction of blood flow in a lumen of a bloodvessel caused by an intraluminal plaque therein. The method includes:(a) inserting an imaging guidewire into the lumen of the blood vessel tothe intraluminal plaque, the imaging guidewire capable of generating across-sectional image of the lumen; (b) propelling a catheter includinga working head over the imaging guidewire towards the intraluminalplaque until the catheter reaches the distal end of the guidewire; (c)scanning the lumen with the imaging guidewire to generate thecross-sectional image of the lumen; (d) radially positioning thecatheter in the lumen by actuating at least one positioning element; (e)monitoring the cross sectional image to ascertain that the working headis positioned at a desired location with respect to the proximal end ofthe intraluminal plaque; and (f) operating the working head to remove atleast a portion of the intraluminal plaque.

According to another aspect of the present invention there is provided asystem for reducing restriction of flow in a lumen of a blood vesselcaused by an intraluminal plaque therein. The system includes:

-   -   (a) an imaging guidewire insertable in the lumen of the blood        vessel, the imaging guidewire capable of generating digital data        which describe a cross-sectional image of the lumen and        communicating the digital data to a central processing unit        (CPU) and further capable of guiding a catheter to the        intraluminal plaque without traversing the plaque;    -   (b) the catheter including a working head, the working head        designed and constructed to remove at least a portion of the        intraluminal plaque;    -   (c) at least one positioning element integrally formed with, or        attached to, the catheter, the at least one positioning element        designed and constructed to radially position the working head        within the lumen of the blood vessel, (d) the CPU and (e) the        actuators, subject to control by the CPU and including: (i) at        least one positioning element actuator responsible for the        control of the at least one positioning device. The CPU is        designed and configured to: (i) accept input from a        physician; (ii) to receive the digital data which describe the        cross-sectional image of the lumen and transform the digital        data into the cross-sectional image displayable upon a display        device; (iii) operate actuators which control components of the        system; (iv) control operation of the positioning element by        means of at least one of the actuators

According to further features in preferred embodiments of the inventiondescribed below, the method further includes iteratively repeating (c)through (f) until the restriction of the lumen has been reduced to thedesired degree.

According to still further features in the described preferredembodiments the method further includes repetition of (e) and (f).

According to still further features in the described preferredembodiments the method further includes iteratively repeated until therestriction of the blood flow in the lumen has been reduced to thedesired degree.

According to still further features in the described preferredembodiments the method further includes advancing the catheter in thelumen.

According to still further features in the described preferredembodiments the method further includes iterative repetition of at leastsome of the actions until the working head traverses the intraluminalplaque.

According to still further features in the described preferredembodiments the intraluminal plaque is of a type selected from the groupconsisting of a primary atherosclerotic lesion, a lesion caused byrestenosis, a lesion residing at least partially within a previouslyimplanted stent, a lesion situated in close proximity to a bifurcationof the lumen of the blood vessel, a vulnerable plaque and a lesion whichtotally occludes the lumen of the blood vessel.

According to still further features in the described preferredembodiments the working head includes at least one cutting edge which isoperative only when the working head moves rotationally.

According to still further features in the described preferredembodiments the at least one positioning element includes at least oneballoon which circumferentially surrounds at least a portion of thecatheter.

According to still further features in the described preferredembodiments the at least one positioning element includes at least oneset of at least three balloons in a single cross sectional plane of thecatheter.

According to still further features in the described preferredembodiments the method further includes at least one additional set ofat least three balloons in a single cross sectional plane of thecatheter.

According to still further features in the described preferredembodiments the inserting, propelling, scanning, radially positioning,monitoring and operating are subject to control by a single centralprocessing unit (CPU).

According to still further features in the described preferredembodiments the single computerized control unit is further subject toinput by a physician operator thereof.

According to still further features in the described preferredembodiments the operating the working head begins prior to a traversalof the plaque by the working head.

According to still further features in the described preferredembodiments the operating of the working head includes rotating theworking bead at a speed of 1 to 100 RPM, more preferably at a speed of 5to 50 RPM, most preferably at approximately 15 RPM.

According to still further features in the described preferredembodiments the CPU is further designed and configured to perform atleast one action selected from the group consisting of: (i) to rotatethe guidewire within the catheter by means of the actuators; and (ii)control operation of the working head.

According to still further features in the described preferredembodiments the CPU further includes at least one item selected from thegroup consisting of a display device and a data input device.

According to still further features in the described preferredembodiments the actuators further includes at least one additionalactuator designed and constructed to perform at least one actionselected from the group consisting of: (ii) rotate the working bead;(iii) advance the catheter within the lumen; and (iv) rotate theguidewire within the catheter. The actuators are subject to control ofthe CPU.

According to still further features in the described preferredembodiments the working head operates intermittently as the cathetertraverses the intraluminal plaque. Traversal is preferably incremental.

According to still further features in the described preferredembodiments the working head includes at least one cutting edge which isoperative only when the working head moves rotationally.

The present invention successfully addresses the shortcomings of thepresently known configurations by providing minimally invasive surgicalsystems and methods of use thereof which permit traversal of a plaquevia sequential removal of portions thereof, each of the portionsselected from a cross sectional image made prior to the traversal.

Implementation of the method and system of the present inventioninvolves performing or completing selected tasks or steps manually,automatically, or a combination thereof. Moreover, according to actualinstrumentation and equipment of preferred embodiments of the method andsystem of the present invention, several selected steps could beimplemented by hardware or by software on any operating system of anyfirmware or a combination thereof. For example, as hardware, selectedsteps of the invention could be implemented as a chip or a circuit. Assoftware, selected steps of the invention could be implemented as aplurality of software instructions being executed by a computer usingany suitable operating system. In any case, selected steps of the methodand system of the invention could be described as being performed by adata processor, such as a computing platform for executing a pluralityof instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin the cause of providing what is believed to be the most useful andreadily understood description of the principles and conceptual aspectsof the invention. In this regard, no attempt is made to show structuraldetails of the invention in more detail than is necessary for afundamental understanding of the invention, the description taken withthe drawings making apparent to those skilled in the art how the severalforms of the invention may be embodied in practice. Wherever possible,like reference numerals have been utilized to identify common elementsthroughout the figures.

In the drawings:

FIG. 1 is a longitudinal sectional view of the distal unit of ARIOaccording to one embodiment of the present invention.

FIG. 2 is a development into a plane view of the closed wave-shapedgroove employed in the present invention.

FIG. 3 is a cross sectional view taken along lines 3-3 of FIG. 1.

FIG. 4 a is a planar view of the working head of the present inventionFIG. 4 b is a cross sectional view taken along lines 4 b-4 b of FIG. 4a.

FIG. 4 c is an isometric view of the working head of the presentinvention.

FIG. 5 is a view in longitudinal section of one alternative embodimentof the distal end of the non-crossing the lesion imaging guidewire ofthe present invention.

FIG. 6 is a view in longitudinal section of an alternative embodiment ofthe working head of the present invention.

FIG. 7 is a diagrammatic illustration showing the way In-Stentrestenosis is removed from inside the stent according to the presentinvention.

FIG. 8 is a diagrammatic illustration showing the way plaque is removedfrom a blood vessel that has a diameter substantially greater thenARIO's diameter, according to the present invention.

FIG. 9 is a diagrammatic illustration showing the way plaque located atbifurcation is removed, according to the present invention.

FIG. 10 is view in longitudinal partial section of the proximal end ofARIO of the present invention.

FIG. 11 is a detailed view in longitudinal section of the O-ring regionshown in FIG. 10.

FIG. 12 is a side view of ARIO's actuator of the present invention.

FIG. 13 is a top view of ARIO's actuator of the present invention.

FIG. 14 is a schematic drawing of the ARIO's controller/computer unit ofthe present invention.

FIG. 15 is an isometric view of an imaging guidewire according to oneembodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of surgical systems and methods of use thereofwhich can be used to increase blood flow in a lumen of a blood vessel ina way which minimizes the risk of damage to surrounding portions of thevessel wall.

Specifically, the present invention can be used to provide improvedcomputerized control for operation of atherectomy instruments whichresults in improved methods for intravascular surgery.

The principles and operation of methods and systems according to thepresent invention may be better understood with reference to thedrawings and accompanying descriptions.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

ARIO combines two main operational features. First, ARIO is able torotate a working head at a very low speed of rotation (less than 100RPM) and at high cutting moment. This is in contrast to previously knowndevices such as AtheroCath™ and the Rotablator™ that rotate at speeds of190,000, and 2,000 RPM respectively. Second, ARIO's working head is notforced through the lesion prior to operation, but is rather slowlyadvanced by small increments while cutting the plaque. This preventsstretching the vessel and resultant damage. As a result of thesefeatures, minimal trauma to the artery is incurred. This is of utmostimportance as medical research has shown that the rate of restenosis isproportional to the trauma caused to the vessel during the angioplastyprocedure.

Thus, the present invention includes several improvements and additionswith respect to my own U.S. Pat. No. 5,350,590. The main improvementsand additions are:

-   -   1) Incorporation of a non-crossing the lesion imaging guidewire.    -   2) Incorporation of positioning balloons.    -   3) Replacing of the hydraulic power by a pushable shaft in the        manner described in my U.S. Pat. No. 5,806,404, FIG. 5.    -   4) Alternative working head that has a cone shape,    -   5) The pins that protrude in the closed wave-shaped groove are        replaced by balls.    -   6) Alternative construction of the closed wave-shaped groove.

For purposes of this specification and the accompanying claims, thephrase “working head” should be construed in its broadest possiblesense. Thus a working head may include, but is not limited to, a rotarycutting nose cone, an abrasive nose cone, a laser energy deliveringdevice, an ultrasound energy delivering device, a heat deliveringdevice, a blunt dissection device or a blunt abrasive device. Thestructural interrelations between the working head and the catheter mayvary depending on the nature of the working head, so long as effectiveguidance of the working head to establish a path across the occlusionduring its intermittent operation is achievable.

It is expected that during the life of this patent many relevantminimally invasive medical imaging techniques that can generate across-sectional view of the blood vessel will be developed and the scopeof the terms “image” and “imaging” is intended to include all such newtechnologies a priori.

The ARIO device comprises three main units: The distal unit, theproximal unit, and two tubes that connect the distal and the proximalunits. ARIO is operated by an actuator that is controlled by acontroller/computer unit (CPU). There are two additional components thatare needed for ARIO's operation: The first is a vacuum pump for removingatheroma debris and blood clots and the second is a therapeutic liquidinfusion pump. These components are commercially available and one ofordinary skill in the art will readily be able to incorporate thecommercially available pumps into the context of the present invention.

Referring now to the drawings, FIG. 1 illustrates a longitudinalsectional view of the distal unit of ARIO. It is shown a blood vessel(21) that has atheroma (22). A pushable shaft (1) moves back and forth,forcing the piston (2) to reciprocate longitudinally in a cylinder (12).Balls (3) located in a closed wave-shaped groove (4) are held in placeby holder (10), and force piston (2) to rotate. The connection of thepushable shaft (1) to the piston (2) is via a bearing adapter (11) andspherical plain bearing (5). Spherical plain bearing (5) decouples thepushable shaft (1) from the rotation movement of the piston (2), i.e.,the pushable shaft (1) is not rotating during the operation. A workinghead (6) is fixedly attached to the piston (2) thus performing acombined longitudinal and unidirectional rotational motion. The pushableshaft (1) is a flexible tube with enough axial stiffness to push andpull piston (2). Pushable shaft (1) is located within torque tube (13).Flexible tube (13) has enough torsion stiffness to counter the momentcreated by the working head (6). The outside diameter of pushable shaft(1) is PTFE coated in order to decrease friction between it and torquetube (13).

The working head (6) contains several sharp edge openings (7) throughwhich the excised atheroma is forced into the cavity (8). The debris isthen removed from the blood vessel by suction of a vacuum pump via theplenum (9). Torque tube (13) is connected to cylinder (12). Threepositioning balloons (14) are mounted on the outer circumference oftorque tube (13). Lumens (15) in the circumference of the torque tube(13) enable inflating/deflating the three positioning balloons (14). Therole of the positioning balloons will be explained in details in FIG. 3and FIG. 7 to FIG. 9.

ARIO accommodates a non-crossing the lesion imaging guidewire (16). Likea standard guidewire it has a body in the form of an elongated flexibletubular member. The imaging guidewire (16) has a proximal end and adistal end. Although imaging guidewire (16) is shown in the drawings tobe straight along the catheter, when the imaging guidewire is outsidethe catheter its distal end resembles a standard guide wire (i.e., itsdistal tip is bent to allow for steerability).

The preferred imaging method used in this embodiment is OpticalCoherence Tomography (OCT). OCT uses infra red light waves that reflectback from the vessel wall to produce a real time computer processedimages cross section. OCT in conjunction with appropriate software canproduce a 3 dimensional image of the blood vessel. The resolution of theimages can reach 10 microns.

The distal end of imaging guidewire (16) comprises a folding mirror (17)that is optically coupled to a grin lens (18), and a preformed curvedtip transparent to light energy (20) that encapsulates the foldingmirror (17). In some embodiments of the invention the folding mirror(17) and the grin lens (18) protrude in front of the working head. Inthe preferred embodiment, shown in FIG. 1, only folding mirror (17)protrudes in front of the working head. This design minimizes the traumato the blood vessel. It is an important feature of the present inventionthat the angle between folding mirror (17) and the catheter axis mayvary, thus enabling the image to be taken at cross sections distally orproximally to the folding mirror (17). In the arrangement shown in FIG.1 the angle is 45 degrees and therefore the image is taken at thesection of the folding mirror (17). An optical fiber (19) is opticallycoupled to the grin lens (18). The optical fiber (19) extends, via acentral lumen, all over the imaging guidewire (16) up to the proximalend where it is coupled to an optical connector (not shown in drawing).For understanding the function of these elements the reader is referredto U.S. Pat. No. 6,445,939 to Swanson.

In order to get an image of the circumference of the blood vessel wall(21) the imaging guidewire (16) is rotated. The number of revolutions ofthe imaging guidewire (16) is dictated by technical requirements e.g.,whether video or still images are required. It is preferable thatsurface (27) of the working head (6), where the imaging guidewire (16)slides, will be Teflon coated. It is to be noted that while the image istaken, the catheter is held in place by the positioning balloons (14).This fact results in a better image.

It is clear that in order to accurately radially position the catheterin the lumen by inflating/deflating the balloons (14) the physician mustknow the relative orientation between the folding mirror (17) and theballoons. This can be done either mechanically or by software. Formechanical orientation the proximal end of the imaging guidewire has amechanical key (66), shown in FIG. 15. The mechanical key (66) can be ofvarious designs e.g., it may have a “D” shape. Whatever the shape of“key” 66, its function is to assure that when the imaging guidewire islocated inside the catheter there is a fixed orientation between thefolding mirror and the balloons.

Alternatively, orientation may be accomplished by software. In this casethe orientation of the folding mirror (17) in regard to balloons (14) isarbitrary. The balloons are inflated sequentially. Following eachinflation, a cross sectional image of the lumen is taken. By comparingthe images the orientation of the folding mirror to the balloons can becalculated.

The rotation of the imaging guidewire inside the catheter can beexploited to facilitate the movement of the atheroma debris towards theproximal end. This is in addition to the vacuum force exerted on thedebris. This goal may be achieved, for example, by incorporating anArchimedes screw into the design of the imaging guidewire. Archimedesscrew (67) is shown in FIG. 1 and also in FIG. 15. Archimedes screw mayextend along the imaging guidewire or only at a small part of theimaging guidewire. In FIG. 1 it is shown a screw that extends fromworking head (6) to the bearing adapter (11). Screw (67) expeditesmovement of plaque debris removed by working head (6) in plenum (9) thatis narrow.

Alternatively the imaging method can be any of the minimally invasivemodalities mentioned above e.g., Ultrasound. Ultrasound produces imagesfrom back-scattered sounds of the vessel wall. The general outer shapeof the imaging guidewire will be the same as for OCT, while the innerparts will be different. For understanding the operation of anultrasound imaging guidewire the reader is referred to U.S. Pat. No.5,095,911 to Pomeranz. It is important to stress that the requirementthat the imaging guidewire rotates along its axis is not mandatory.Imaging guidewires that can produce an image without rotation are known,e.g., U.S. Pat. No. 5,947,905 to Hadjicostis which describes anultrasound transducer where the signals are received from an array ofsensors located all around the circumference of the imaging guidewire.

FIG. 2 is a development into a plane view of the closed wave shapedgroove (4). The closed wave shaped groove (4) comprises three types ofsections. A positive slopped section (4 a), a negative sloped section (4b) and a parallel to catheter axis section (4 c). The end points of thepositive slopped section (4 a) are located distally to the end points ofthe negative sloped section (4 b), at a distance that is the length ofthe parallel to catheter axis section (4 c). The parallel to axissection (4 c) is connecting the end points of the two sloped sections (4a and 4 b). It is the aim of the following discussion to show that theclosed wave shaped groove (4) transforms a reciprocating motion ofpiston (2) into a combined reciprocating and uni-directional motion ofpiston (2). Lets start with an arbitrary position of ball (3) in theclosed wave shaped groove (4). It is important to understand that theball (3) is fixed in the catheter while closed wave shaped groove (4)slides over it. When distal piston (2) is pulled proximally it alsoperforms a clock-wise rotation when viewed from proximal end. Thismotion continuous until end point (4 a-1) reaches the center of the ball(3). Then if the longitudinal motion of piston (2) is changed i.e, it ispushed distally, end point (4 b-1) will reach the center of ball (3).This part does not result in rotation of piston (2). However, if piston(2) continues to be pushed distally the negative sloped section (4 b)will slide over ball (3) causing piston (2) also to perform a clock-wiserotation when viewed from proximal end. This motion will continue untilend point (4 b-2) reaches the center of ball (3). The above discussioncan be repeated for other apexes of the closed wave shaped groove (4).Thus, it was shown that the closed wave shaped groove (4) transforms areciprocating motion of piston (3) into a combined reciprocating anduni-directional rotational motion of piston (3).

In order to cause piston (2) to rotate in the opposite direction, (i.e.counter-clock-wise rotation, when viewed from proximal end), the endpoints of the positive slopped section (4 a) must be located proximallyto the end points of the negative sloped section (4 b), at a distancethat is the length of the parallel to catheter axis section (4 c).

The stroke of the closed wave-shaped groove can vary. For example, inthe device shown in FIG. 1, which is a scaled drawing of ARIO 2.3 mm(=7F) the stroke is 2 mm.

FIG. 3 shows the operation of the positioning balloons (14). Theposition of the catheter is a resultant of the forces applied by thethree positioning balloons (14) on the lumen's wall. If the balloons areinflated by unequal pressures the catheter will move off axis. In thedrawing positioning balloon (14 a) is inflated more then positioningballoons (14 b) and (14 c). Therefore, the catheter will move downwards.Positioning balloons (14 a-c) can be replaced by other positioningelements such as mechanical arms that are located on the outercircumference of the catheter and are pushed during deployment againstthe lumen's wall. Also, are shown the lumens (15) one for each of thepositioning balloons (14). An additional therapeutic lumen (26) is usedfor injection of therapeutic liquid to the area of the excised atheroma.The therapeutic lumen may also serve additional purposes. For example,it has been observed that there is a substantial attenuation in theimaging signal resulting from the presence of blood. In order toovercome this problem injection of saline at the place of imaging isrequired. The therapeutic lumen can serve this purpose. Alternatively,the saline can be injected via an additional lumen or via the imagingguidewire itself.

It is to be noted that the three positioning balloons (14) are connectedto a control system (located outside the patient's body) that measuresand regulates the pressure in each of the positioning balloons (14). Thecontrol system assures that the pressure in any of the positioningballoons (14) will not rise above a predetermined threshold pressure(e.g., 4 atmospheres). This is an important feature as it eliminatesstressing of the vessel walls. Balloons can be manufactured fromdifferent materials (PET, latex, silicon etc.). It is preferred to uselow pressure elastomeric balloons, typically made of latex or siliconethat stretch 100-600% when pressure is applied, and return to theiroriginal size when pressure is released.

An additional embodiment comprises a single positioning balloon 14. Inthis case the catheter will always be positioned on the longitudinalaxis of the lumen. However, this embodiment limits the operation ofARIO. A disadvantage of using one positioning balloon is that bloodcannot flow in the artery when the balloon is inflated, thus causingpain to the patient. In the case of three or more balloons, blood canalways flow via the gaps between the balloons. FIGS. 7 to 9 show theoperational advantages of using multiple positioning balloons (14).

FIGS. 4 a, 4 b and 4 c show the cone shaped working head (6). It canhave one or more openings (7) with sharp edges (25). The picturedembodiment shows five openings (7). It is the goal of this design tohave a cutter that is safely inserted in the blood vessel in spite ofhaving very sharp edges. Openings (7) are very narrow, so that debris ofthe excised atheroma that enters cavity (8; see FIG. 1) cannot gooutside of working head (6) into the blood vessel. The opening (7) ismanufactured with a cutter (e.g., laser cutter). Sharp edges (25) arecreated if the cutter is positioned so that it cuts perpendicular to aplane passing through the cutter (6) axis and the cutting pass (7 a) isparallel to the contour line of the cone. When looking on the workinghead (6) axially towards the proximal direction, the sharp edges (25)are not seen. This means that if the working head (6) comes in contactwith the vessel's wall, the wall touches a smooth surface, rather thanthe sharp edges. This permits safe insertion of the device into theblood vessel. The cutting of the atheroma is possible only when workinghead (6) rotates.

FIG. 5 shows an imaging guidewire (16) that has the same diameter (e.g.,350 microns) along its entire length. This small diameter guidewireincludes a small diameter lens (18), as described in U.S. Pat. No.6,445,939 to Swanson. This construction allows only a small part of theimaging guidewire (16) to protrude in front of working head (6). Thisminimizes the trauma to the blood vessel. The part that protrudesincludes folding mirror (17) that is located in preformed curved tiptransparent to light energy (20). Also are shown lens (18) and opticalfiber (19). Imaging guidewire (16) rotates on a sliding surface (27). Aring (28) is fixed to distal end of imaging guidewire (16), thuspreventing imaging guidewire (16) from being pulled back beyond slidingsurface (27).

FIG. 6 shows an alternative embodiment of the working head (6). Theworking head (6) has opening (7) on its distal surface. The distal endof imaging guidewire (16) is substantially bigger then its other parts.In order to reduce the part of the imaging guidewire (16) that extendsin front of working head (6) a recess (29) is done in the front face ofworking head (6). This construction minimizes the trauma to the bloodvessel. The part that protrudes out of working head (6) front faceincludes only folding mirror (17) that is located in preformed curvedtip transparent to light energy (20). Imaging guidewire (16) rotates ona sliding surface (27). Also are shown lens (18) and optical fiber (19).This embodiment has advantages when used for clearing total occlusions(22).

FIG. 7 shows the struts of a stent (30) that is deployed off bloodvessel axis. This phenomenon can happen either during the deployment ofthe stent or subsequently. In order to excise the in-stent Restenosis(31), without damaging the stent (30), the catheter (32) must bepositioned on the stent axis rather then on the blood vessel axis. Theradial positioning is achieved by positioning balloons (14).

FIG. 8 shows a catheter (32) that has a diameter that is significantlysmaller than the diameter of the blood vessel. In minimally invasiveprocedures it is preferred to use a small diameter catheter (e.g., nomore then 2.3 mm=7 F), so that only a small incision in the groin isneeded to introduce the catheter (32). Nonetheless, this small diametercatheter (32) must remove the atheroma that may completely traverse thecross section of the blood vessel (21). The positioning balloons enablethe physician to move the catheter radially all over the cross sectionof the blood vessel. The physician can define an imaginary border line(33) in which he wants the atheroma to be removed. The border line (33)diameter is smaller then the inside diameter of the blood vessel (21),thus reducing the risk of blood vessel perforation. It is clear, fromgeometric considerations, that initial atheroma (22) can never betotally removed in this procedure. Two sequential positions of thecatheter (32) and (32 a) are shown in the drawing. Some protrusion ofatheroma (22 a) will always be left. The protrusion (22 a) can bedefined by its height, as shown in the drawing. In order to make theprotrusion height smaller, and thus making the inner surface of bloodvessel (21) smoother, more sequential catheter positioning with closerdistances between their centers must be done. The sequential radialpositioning of the catheter can be done either manually orautomatically.

FIG. 9 shows how positioning balloons 14 are used to remove atheroma(22) at bifurcation. In this case the positioning balloons are used toposition the catheter (32) not only off axis but also at an angle to theaxis of the blood vessel (21). This can be done if an additional arrayof 3 positioning balloons (14 d, 14 e, 14 f) (14 f is not shown indrawing) is added along the catheter (32). If positioning balloon (14 a)is inflated more than positioning balloon (14 d), catheter (32) will beforced to move towards the atheroma (22).

Although my U.S. Pat. No. 5,697,459 shows a similar arrangement of 6balloons, their main purpose is to enable the drill to be selfpropelled. Therefore, that earlier work depicts 3 balloons located onthe device body and 3 other balloons located on the working head.According to the present invention (ARIO) all the positioning balloonsare all located on the catheter body.

FIG. 10 shows the proximal end of ARIO. The distal end of ARIO is shownfor reference only. It shows a proximal piston (35) that moves back andforth in a proximal cylinder (36). The stroke of this movementcorresponds to stroke of the closed wave-shaped groove (4) shown inFIGS. 1 and 2. The velocity of proximal piston (35) can be very low. Inthe preferred embodiment it is 1 mm/sec. This velocity is transformed atthe distal end of ARIO to 15 RPM of the working head (6).

Proximal cylinder (36) is fixedly attached to torque tube (13). Aninfusion connector (37) is mounted on proximal cylinder (36). Infusionconnector (37) is opened to therapeutic lumen (26; see FIG. 3). Aninfusion pump is connected to the infusion connector (37) to delivertherapeutic liquid, via therapeutic lumen (26; see FIG. 3), to the siteof the atheroma. Infusion pumps suited for use in the context of thepresent invention are commercially available. One of ordinary skill inthe art will be easily able to incorporate such a commercially availabledevice into the present invention. Three balloon connectors (38) (forclarity only one is shown) are connected to proximal cylinder (36).Balloon connectors (38) are opened to balloon lumen (15; see FIG. 3).Proximal cylinder (36) includes a groove (39) on its circumference.Groove (39) is used to mount proximal cylinder (36) on ARIO actuator (Itis explained in FIG. 12 and FIG. 13).

Proximal piston (35) is fixedly attached to pushable shaft (1). A vacuumconnector (40) is mounted on proximal piston (35). Vacuum connector (40)is opened to passage (41), that is connected to plenum (9) shown inFIG. 1. A vacuum pump (not shown here) is connected to vacuum connector(40) for aspirating the atheroma debris via passage (41) and plenum (9)(see FIG. 1). Proximal piston (35) includes a groove (42) on itscircumference. Groove (42) is used to mount proximal piston (35) on ARIOactuator. (It is explained in FIG. 12 and FIG. 13). An imaging guidewirenut (43) is attached to the proximal end of proximal piston (35).

FIG. 11 is an enlargement of detail 11 shown in FIG. 10. Imagingguidewire nut (43) has a central passage (44) through which imagingguidewire (16) passes. When imaging guidewire nut (43) is tightened itsqueezes on an O-ring (45) thus keeping the proximal piston passage (41)vacuum tight. O-ring (45) allows imaging guidewire (16) to rotate, whilekeeping the vacuum tight. The rotation of imaging guidewire (16) isneeded for the imaging process.

FIGS. 12 and 13 describe ARIO's actuator. FIG. 12 is a side view of theactuator and FIG. 13 is a top view of the actuator. A base (48) is fixedto the patient bed. A linear slide (49) is attached to an advancementlinear actuator (50). Both are mounted on base (48). They serve foradvancing ARIO in the blood vessel. The advancement is incremental witha movement that is preferably less then the stroke of the closedwave-shaped groove (4) (see FIG. 2). A bracket (51) is mounted on top oflinear slide (49). Groove (39) of proximal cylinder (36) (see FIG. 10)fits into bracket (51) and secured in place by clamp (52). Linear slide(54) is attached to a reciprocating linear actuator (55). Both aremounted on bracket (51). An adapter (60) is mounted on top of linearslide (54). Groove (42) of proximal piston (35) (see FIG. 10) fits intoadapter (60) and secured in place by clamp (53). Back and forth motionof reciprocating linear actuator (55) causes reciprocation of proximalpiston (35) and pushable shaft (1) and eventually results inlongitudinal and rotational movement of working head (6) (see FIG. 1).

FIG. 13 also depicts a balloon inflating/deflating system. It comprisesa syringe pump (56) that is connected to balloon connector (38) (seeFIG. 10). Syringe pump (56) is operated by balloon linear actuator (58).A pressure transducer (57) measures the pressure in syringe pump (56).This pressure is monitored by a controller/computer unit (see FIG. 14and explanation hereinbelow). For clarity, only one ballooninflating/deflating system is shown, but the actual system may, forexample, contain three or six balloons which are independentlyregulated.

ARIO's actuator comprises also an imaging guidewire motor (59). Theimaging guidewire (16) is secured to motor (59). In order to take acircumferential scan of the artery the imaging guidewire must rotate.This is done by imaging guidewire motor (59). The signals of thescanning are sent to the computer via optical fiber (19).

FIG. 14 is a schematic drawing of ARIO's control system. It comprises acontroller/computer unit (63) and a display (64). Thecontroller/computer unit (63) governs all the functions of the system.The inputs to the controller/computer unit are: a) balloon pressure b)imaging data c) physician inputs: advancement velocity, reciprocationvelocity, maximum balloon pressure, balloon positioning, cutting borderline (33) (see FIG. 8). The outputs from the controller/computer unit(63) are directed to: a) advancement linear actuator (50); b)reciprocating linear actuator (55); c) imaging guidewire motor (59); d)balloon linear actuator (58) and e) processed optical image of the bloodvessel to the display. The controller/computer unit (63) controls themovement of balloon linear actuator (58) in such a way that while one ofthe positioning balloons (14) moves in a desired direction, the pressurein the other positioning balloons does not exceed a predeterminedthreshold pressure (e.g., 4 Atmospheres). During the operation thephysician sees a real time cross sectional images of the blood vessel.It is clear that the computer can construct a 3 dimensional image fromthe cross sections. The physician can see the atheroma in 3 dimensionalimage before and after operation. He can find out how much volume ofatheroma was removed, calculate the surface roughness after theoperation etc.

The operation of ARIO can be done automatically from the step that ARIOis positioned proximally to the lesion. However, the physician canalways take control of the operation. Physician control may be either bydirect physical manipulation of components of the system, or via inputto the CPU.

The system further includes safety provisions, e.g., the electricalcurrent of the advancement linear actuator (50) is limited so that noexcessive force is applied on the blood vessel during advancement. Thesame applies to reciprocating linear actuator (55), so that the momentapplied by working head is limited etc. The physician will be notifiedvisually and/or audibly of any problem in the system.

FIG. 15 illustrates clearly an imaging guidewire (16) with a mechanicalkey (66) and Archimedes screw (67). These features are illustratedwithin catheter (32) in FIG. 1, described hereinabove.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

1. A method for reducing restriction of blood flow in a lumen of a bloodvessel caused by an intraluminal plaque therein, the method comprising:(a) inserting an imaging guidewire into the lumen of the blood vessel upto the intraluminal plaque without traversing the plaque, said imagingguidewire having a distal tip that includes imaging components capableof generating a cross-sectional image of the lumen, at least a portionof said distal tip having a diameter that is larger than a rest of saidguidewire having a smaller diameter; (b) propelling a catheter over saidimaging guidewire towards said intraluminal plaque until said catheterreaches said distal end of said guidewire, said catheter having aworking head located at a distal tip of said catheter, said working headconfigured for removal of at least a portion of the intraluminal plaque,said catheter and said working head deployed on said imaging guidewireso as to accept passage of said rest of said imaging guidewire havingsaid smaller diameter axially through a central region of said workinghead and said catheter as said catheter propelled towards saidintraluminal plaque, and when said catheter reaches said distal tip ofsaid guidewire at least a portion of said imaging components arepositioned inside said working head and a portion of said distal tip theonly element of either of said imaging guidewire and said catheterextending in front of said working head; (c) scanning the lumen withsaid imaging guidewire to generate said cross-sectional image of thelumen; (d) positioning said catheter in the lumen by actuating at leastone positioning element; (e) monitoring said cross sectional image toascertain that said working head is positioned at a desired locationwith respect to said proximal end of the intraluminal plaque; and (f)operating said working head to remove at least a portion of theintraluminal plaque.
 2. The method of claim 1, further comprisingrepetition of (c) through (f).
 3. The method of claim 2, iterativelyrepeated until the restriction in the lumen has been reduced to adesired degree.
 4. The method of claim 3, further comprising advancingthe catheter together with said distal tip of said guidewire in thelumen.
 5. The method of claim 4, iteratively repeated until said workinghead traverses said intraluminal plaque.
 6. The method of claim 1,wherein said intraluminal plaque is of a type selected from the groupconsisting of a primary atherosclerotic lesion, a lesion caused byrestenosis, a lesion residing at least partially within a previouslyimplanted stent, a lesion situated in close proximity to a bifurcationof the lumen of the blood vessel, a vulnerable plaque and a lesion whichtotally occludes the lumen of the blood vessel.
 7. The method of claim1, wherein said working head includes at least one cutting edge which isoperative only when said working head moves rotationally.
 8. The methodof claim 1, wherein said positioning of said catheter in the lumen isimplemented such that said at least one positioning element includes atleast one balloon which circumferentially surrounds at least a portionof said catheter.
 9. The method of claim 1, wherein said positioning ofsaid catheter in the lumen is implemented such that said at least onepositioning element includes at least one set of at least three balloonsin a single cross sectional plane of said catheter.
 10. The method ofclaim 9, wherein said positioning of said catheter in the lumen isimplemented so as to further include at least one additional set of atleast three balloons in a single cross sectional plane of said catheter.11. The method of claim 1, wherein said inserting, propelling, scanning,positioning, monitoring, operating are subject to control by a singlecentral processing unit (CPU).
 12. The method of claim 11, wherein saidsingle CPU is further subject to input by a physician operator thereof.13. The method of claim 1, wherein said operating said working headbegins prior to a traverse of the plaque by said working head.
 14. Themethod of claim 1, wherein said operating of said working head includesrotating said working head at a speed of 1 to 100 RPM.
 15. The method ofclaim 1, wherein said operating of said working head includes rotatingsaid working head at a speed of 5 to 50 RPM.
 16. A system for reducingrestriction of flow in a lumen of a blood vessel caused by anintraluminal plaque therein, the system comprising: a) an imagingguidewire insertable in the lumen of the blood vessel up to theintraluminal plaque without traversing the plaque, said imagingguidewire having a distal tip that includes imaging components capableof generating digital data which describe a cross-sectional image of thelumen and communicating said digital data to a central processing unit(CPU) and further capable of guiding a catheter to the intraluminalplaque without traversing the plaque, at least a portion of said distaltip having a diameter that is larger than a rest of said guidewirehaving a smaller diameter; (b) a catheter including a working headlocated at a distal tip of said catheter, said working head designed andconstructed to remove at least a portion of the intraluminal plaque,said working head deployed on said imaging guidewire so as to acceptpassage of said rest of said imaging guidewire having said smallerdiameter axially through a central region of said working head and saidcatheter as said catheter is propelled towards said intraluminal plaqueuntil said catheter reaches a distal tip of said guidewire such that atleast a portion of said imaging components are positioned inside saidworking head and a portion of said distal tip is the only element ofeither of said imaging guidewire and said catheter extending in front ofsaid working head; (c) at least one positioning element integrallyformed with, or attached to, said catheter, said at least onepositioning element designed and constructed to position said workinghead within the lumen of the blood vessel; (d) a CPU designed andconfigured to: (i) accept input from a physician; (ii) to receive saiddigital data which describe said cross-sectional image of the lumen andtransform said digital data into said cross-sectional image displayableupon a display device; (iii) operate actuators which control componentsof the system; and (iv) control operation of said positioning element bymeans of at least one of said actuators; and (e) one or more actuators,subject to control by said CPU and including: (i) at least onepositioning element actuator responsible for the control of said atleast one positioning device.
 17. The system of claim 16, wherein saidCPU is further designed and configured to perform at least one actionselected from the group consisting of: (i) to rotate said guidewirewithin said catheter by means of said actuators; and (ii) controloperation of said working head.
 18. The system of claim 16, wherein saidCPU further includes at least one item selected from the groupconsisting of a display device and a data input device.
 19. The systemof claim 16, wherein said actuators further includes at least oneadditional actuator designed and constructed to perform at least oneaction selected from the group consisting of: (i) longitudinallyreciprocate and rotate said working head; (ii) advance said catheterwithin the lumen; (iii) rotate said guidewire within said catheter;wherein said actuators are subject to control of said CPU.
 20. Thesystem of claim 16, wherein said working head is configured to operateintermittently as said catheter traverses said intraluminal plaque. 21.The system of claim 16, wherein said working head includes at least onecutting edge which is operative only when said working head movesrotationally.
 22. The system of claim 16, wherein said at least onepositioning element includes at least one balloon whichcircumferentially surrounds at least a portion of said catheter.
 23. Thesystem of claim 16, wherein said at least one positioning elementincludes at least one set of at least three balloons in a single crosssectional plane of said catheter.
 24. The system of claim 23, furtherincluding at least one additional set of at least three balloons in asingle cross sectional plane of said catheter.
 25. The system of claim16, wherein said working head is configured such that operation of saidworking head begins prior to a traverse of the plaque by said workinghead.
 26. The system of claim 16, wherein operation of said working headincludes rotating said working head at a speed of 1 to 100 RPM.
 27. Thesystem of claim 16, wherein operation of said working head includesrotating said working head at a speed of 5 to 50 RPM.
 28. The system ofclaim 16, wherein said imaging guidewire further includes a imagingsensor and wherein said catheter is positionable upon said guidewire sothat only said imaging sensor protrudes from said working head in adirection facing the plaque.
 29. The system of claim 16, wherein anArchimedes screw is further incorporated into the design of said imagingguidewire in order to facilitate removal of at least a portion of theplaque.
 30. The system of claim 16, wherein said catheter includes atleast one therapeutic lumen.
 31. The system of claim 16, wherein saidcatheter includes a central vacuum lumen.
 32. The system of claim 16,wherein said catheter and said guidewire are configured to cross thelesion together by advancing said catheter together with said distal tipof said guidewire in the lumen.
 33. A system for reducing restriction offlow in a lumen of a blood vessel caused by an intraluminal plaquetherein, the system comprising: (a) an imaging guidewire insertable inthe lumen of the blood vessel, said imaging guidewire has a distal tipthat includes at least an imaging sensor and at least a portion of saiddistal tip has a diameter that is larger than a rest of said guidewirehaving a smaller diameter, said imaging guidewire capable of generatingdigital data which describe a cross-sectional image of the lumen andcommunicating said digital data to a central processing unit (CPU) andfurther capable of guiding a catheter to the intraluminal plaque withouttraversing the plaque; (b) said catheter includes a working head, saidworking head deployed on said imaging guidewire so as to accept passageof said rest of said imaging guidewire having said smaller diameteraxially through a central region of said working head and said catheteras said catheter is propelled over said imaging guidewire until saidworking head reaches said distal tip, said working head designed andconstructed to remove at least a portion of the intraluminal plaque; and(c) at least one positioning element integrally formed with, or attachedto, said catheter, said at least one positioning element designed andconstructed to radially position said working head within the lumen ofthe blood vessel.
 34. The system of claim 16, wherein said at least aportion of said distal tip that is larger than the rest of the guidewireis a preformed curved tip.
 35. The system of claim 16, wherein said atleast a portion of said distal tip that is larger than the rest of theguidewire is a ring that is fixed to distal end of imaging guidewire.36. The system of claim 16, wherein said at least a portion of saiddistal tip has a diameter of up to 800 microns, while the rest of theguidewire has a diameter of up to 350 microns.